Associations between LBP and activities of daily living
Activities of daily living (ADL) are various functional activities that may range from basic ones, such as walking or bending, to more complex activities (also called instrumental activities of daily living, IADL), such as cooking, bathing or getting dressed, in other words activities which enable independent living [14, 15]. There seems to be a consensus across studies that LBP is associated with problems in ADL. An Austrian study in the general population aged 65 years and over found a clear association between LBP and problems in ADL with an odds ratio (OR) 2.01 (95% confidence interval, CI 1.57–2.57) and IADL with OR 2.17 (95% CI 1.82–2.59), adjusted for sociodemographic, lifestyle and health-related parameters. Another Austrian cross-sectional study of older adults with and without osteoporosis, osteoarthritis and chronic back pain using a nationally representative dataset reported that doing heavy housework, bending or kneeling, climbing stairs up and down without walking aids and walking 500 m without a walking aid were the most problematic ADLs in all groups . Interestingly, people with chronic LBP reported a much larger number of problematic ADLs compared to those with other musculoskeletal diseases or without them .
A Thail cohort study (N = 42,785; 80% aged between 30 and 50 years) showed that 30% of the cohort participants reported LBP, where approximately 6% of the cohort reported difficulties in bending, 3.1% had difficulties in walking a 100 m, 2.2% could not climb stairs, and a further 2.9% had problems when dressing. This longitudinal cohort study reported a time-dependent increasing gradient in the functional limitation across all activities . This study provided interesting results not only due to its longitudinal design but also gave insights into the LBP problems occurring in middle income level countries, which are seldom presented in research . As mentioned in the introduction, the high prevalence of LBP is a known public health issue in industrialized countries ; however, longitudinal studies investigating LBP as a disability factor are rare. Some studies however, showed that LBP is an independent factor that worsens the self-reported disability level and makes ADL much harder for people who are already living with disabilities. For example, results from the Women’s Health and Aging Study (n = 1002) showed that 42% of older women with disability reported LBP. After multivariate adjustments, women with severe back pain were 3–4 times more likely to report difficulties with light housework or shopping as well as having an increased likelihood of issues with various mobility tasks . Results of this study need to be interpreted in the light of the study participants, namely older women (30% of participants older than 85 years) who were already living with a serious disability. Similar results came from a cohort of patients living with rheumatoid arthritis (RA). In a study population of 281 patients with RA, 53.4% reported LBP over a 6-month period. Those patients who reported experiencing LBP presented with significantly higher disability in ADL compared to RA patients without LBP. This study found a moderate effect of LBP, which was enough to demonstrate a clinical relevance of LBP comorbidity in this patient group . Some studies looked into patient groups with an objectively confirmed etiology of reported LPB. A Turkish study investigated differences in ADL in patients with LBP resulting from lumbar disc herniation between those who received conservative treatment and those who underwent surgery. Prior to treatment they found that patients in both groups reported similar issues, mostly problems with prolonged standing, lifting weights and socializing. At follow-up (3 months following treatment) there seemed to be no differences in ADL that the patients had problems with; however, it is important to note that the patients who received conservative treatment reported worsening in terms of experienced pain . These results need to be interpreted with caution as the study did not report on surgical or conservative treatment protocols, post-surgery complications, physiotherapy or occupational therapy that the study patients underwent.
Studies of both the general population as well as populations of patients with other chronic illnesses or disabilities reach a consensus that LBP causes problems in functional capacity and performing ADL [21,22,23]. The reason for this association may be in the deconditioning syndrome (complex process of physiological changes due to periods of inactivity ), which has been reported in substantial numbers of patients with chronic LBP issues [25,26,27]. Furthermore, LBP and ADL deficits do not only occur together very often. If chronic pain and ADL deficits coincide, they work synergistically towards an adverse outcome. Subjects affected by both ADL deficits and chronic pain showed a strong synergistic effect towards health care utilization. This means that healthcare utilization was much higher than could be expected from the mere addition of the health care utilization due to ADL deficits plus health care utilization due to chronic pain .
Association between LBP and work ability
The LBP is the most recurrent of all chronic conditions experienced by the working population and is one of the leading causes of disability and absence at work associated with high socioeconomic impact. As mentioned in the introduction, LBP is associated with very high costs, with indirect costs (which include loss of productivity or loss of working days) representing more than two thirds of the total costs . The results of two US national surveys showed that more than 100 million working days are lost each year due to LBP [30, 31]. In Austria musculoskeletal problems accounted for the highest number of sick leave days in 2017, with LBP being one of the most commonly reported problems [11, 32]. One of the reasons why LBP has a strong influence on working ability and loss of productivity is the high prevalence in adulthood during the most economically productive ages (30–60 years) [3, 33].
Epidemiological analyses point to several work-related activities (lifting or pushing weights, vibration exposure, various ergonomic issues) that may be the cause of LBP or at least increase the risk for recurrence [34, 35]. This leads to increased disability, absenteeism and employee turnover. Therefore, not surprisingly, LBP ranks among the most expensive medical conditions . The LBP seems to be very prevalent among healthcare workers, with the 1‑year prevalence being reported between 45% and 77%, which is more compared to other occupations .
A study by Nordstoga et al. of 165 patients with non-specific LBP seeking primary physiotherapy reported that higher work ability was associated with less disability, less pain and higher quality of life . Increased psychological distress caused by LBP and the number of pain sites were associated with higher disability, more pain, and lower quality of life. After 3 months follow-up improvements in work ability showed significant associations with improvement in disability, pain and quality of life . These results support the notion that improving the patients’ ability to work will have farther reaching and overall effects on multiple health outcomes. Interestingly, the same study reported that reduced psychological distress was only associated with improvements in pain but not work ability. Another study from Nordstoga et al. further showed that fear of pain reoccurrence leads to avoidance of certain movements, called fear-avoidance beliefs (FAB), which were associated with both levels of reported disability and work ability . Moreover, a Finnish cross-sectional study of 219 female healthcare workers with non-specific LBP investigating pain level, physical functioning and ability to work reported that the strongest associations of better work ability were lower work-induced lumbar exertion, better perceived work recovery, lower depression and lower work-related FABs .
Interesting results come from a Japanese study by Tsuboi et al. that looked into the associations between presenteeism and FAB among workers with LBP providing care for old people . Presenteeism is the opposite of a more well-known concept of absenteeism and may be defined as workers being on the job but because of illness or other medical conditions, not fully functioning . Interestingly, presenteeism is also associated with higher socioeconomic burden with some studies reporting the costs being 2–5 times higher and losses of productivity being 2–3 times higher than those associated with absenteeism . A recent Japanese study reported the costs of absenteeism of US$520 and presenteeism at US$3055 per patient per year . The adjusted model of this study showed that higher scores of kinesophobia (fear of movement) resulting from LBP were associated with higher presenteeism and there were significant associations between kinesophobia scores and all the work ability subscales (e.g. time management, mental interpersonal demands, physical demands and output demands).
Association between LBP and sexual function
Sexual function and sexuality have an effect on patients’ overall quality of life; however, questions regarding sex, sexual function or practices are often overlooked by researchers and practitioners but also patients and study participants [44, 45]. For example, an Australian study found that nearly half of the respondents using the Oswestry Disability Index, a widely used instrument for assessing chronic LBP, did not complete the section specific to sex life . The study reported that there are widespread anecdotal beliefs that questions on sex life are inaccurately answered and that the mere presence of a question on sexuality may repel some participants from filling it out; however, this was not found to be accurate in this study and other studies that reported an overall response rate to sexuality questions of 97%. The study also found that those participants who responded to the question on sexuality did so accurately ; however, studies remain scarce in this respect.
An Austrian study, carried out within the framework of regular health check-ups in supposedly healthy people, found subjects who reported sexual dissatisfaction had a threefold higher chance of being affected by joint and muscle pain in men and a 2.64 times higher chance in women . An early Swedish study (published in 1981) in 35 male and 25 female participants investigated various sexual outcomes and chronic back pain . Almost half of both male and female participants reported an overall reduction in intercourse with 37% of men reporting a decrease in erections and 23% of men and 28% of women reporting a decrease in the frequency of orgasms. Coital positions also changed in frequency before and after the onset of LBP in both groups. Half of the male respondents and 80% of women named fatigue as a reason that prevents them fully enjoying sex. Overall, 54% of men and 52% of women felt the general satisfaction with sex decreased after the onset of LBP. The authors hypothesized about the underlying effect of depression as a common psychiatric comorbidity of LBP but also that painful muscle hypertonia may be a result of somatic conversion . Results of this study were confirmed in subsequent studies that consistently showed reduction in sex frequency following LBP as well as more or worsening pain as a result of coitus as well as discomfort and problems in finding the appropriate sexual position [49,50,51,52]. Results from a more recent Iranian study comparing 702 men and women with LBP with 888 healthy controls showed that the prevalence of sexual issues in female patients with chronic LBP was 71.1% while 36.8% of women without LBP had corresponding results. Erectile dysfunction was reported by 59.5% of men with LBP, compared to 24.5% in healthy men . Better sexual functioning in both males and females was associated with younger age, shorter duration of LBP, lower body mass index (BMI), higher education level, unemployment, being physically active, being on shorter sick leave, lower pain and disability, higher family income and lower depressive and anxiety symptoms and better psychological functioning . Results of these studies led to a hypothesis that sexual issues are not only psychological but may be also mechanical.
To elucidate the spinal movements in healthy males, a study by Sidorkewicz and McGill made a biomechanical analysis of spine movements and postures during coitus . Based on the measurements, recommendations on sexual positions for males with LBP were made. A rear entry position where the female is in the quadruped position supporting her upper body with her elbows is the most recommended sexual position for flexion-intolerant men. Side lying positions were least recommended. For patients who were motion-intolerant, coital movements from spine dominant to hip dominant are recommended . This study, however, did not take potential problems of the female partner into account nor did it investigate spinal motions in non-heterosexual couples or sexual activities outside vaginal intercourse. Further investigations with more inclusivity and diversity in sexual positioning, practice and sexual orientation of couples included should be done. A systematic review in musculoskeletal pain and sexual functioning in women, albeit not focusing specifically on LBP, concluded that there is still a knowledge gap in the effects of musculoskeletal disorders and sex related outcomes; however, fatigue, medication use and relationship adjustment were found to affect sexuality in women as much as chronic illness . Interestingly a French study found that women with LBP reported greater reduction in coitus frequency, more discomfort and more overall interference in sexual lives compared to women with neck pain . Countrary to the biomechanical analysis recommendations by Sidorkewicz and McGill , Rosenbaum suggests the side lying position as most appropriate for women with LBM .
In a study including 742 Iranian patients with chronic LBP the mediation effect of sexual functioning on pain and depression was investigated. The study confirmed that in both men and women depressive symptoms showed a significant association with pain intensity and that both models were significantly mediated by sexual functioning, with a medium to large effect in men and medium effect in women .